After Effects (as of version 16, released 2020) uses the V8 Javascript engine to interpret expressions. This is the same as used in many web browsers, such as Chrome.

It's pretty easy to test if it follows BODMAS (The **O** in which stands for **Order** BTW). On a text layer <kbd>alt / opt</kbd>-click the stop watch for text source and paste this:

    let brackets = 2 * (1 + 1);
    let order = Math.pow(2, 2) + 1;
    let divMult = 1 + 2 * 2 + 4 / 2;
    "Brackets: 2 * (1 + 1) should be 4, result: " + brackets + "\n" +
    "Order: 2^2 + 1 should equal 5, result: " + order + "\n" + 
    "Division and Multiplication: 1 + 2 * 2 + 4 / 2 should equal 7, result: " + divMult + "\n"

Spoiler alert: it does.
[![result of entering the expression in a text layer, showing correct results for BODMAS][1]][1]


  [1]: https://i.sstatic.net/bwrX4.png